Aerojet Propulsion Systems to Maneuver Radiation Belt Storm Probes

SACRAMENTO, Calif., Aug. 30, 2012 – Aerojet, a GenCorp (NYSE: GY) company, announced today that United Launch Alliance’s Atlas V successfully lofted NASA’s twin Radiation Belt Storm Probes (RBSP) on a two-year mission to explore the Van Allen belts. Each RBSP relies on an Aerojet integrated propulsion system that will be used throughout the mission to position the satellites.

The Atlas V launching RBSP also used eight Aerojet retro-rockets to separate the Centaur upper stage from the Atlas, and 12 monopropellant hydrazine thrusters on the Centaur upper stage for roll, pitch, yaw and settling burns.

Aerojet’s RBSP propulsion systems use monopropellant hydrazine and each system includes three propellant tanks, eight Aerojet MR-103G 0.2 lbf thrusters, two Aerojet-built diode boxes, and a variety of other components including, tubing, thermal control and telemetry. The systems were designed, built, assembled and tested at Aerojet’s Redmond, Wash. facility and shipped to Johns Hopkins University Applied Physics Laboratory (JHU/APL) in October 2010. JHU/APL and Aerojet also have added additional shielding to protect the satellites from the radiation they expect to experience during the mission.

"The Radiation Belt Storm Probes will essentially be in harm’s way as we seek to understand the dynamics of the high energy protons that can damage instruments and be a hazard to astronauts," said Aerojet Vice President of Space and Launch Systems, Julie Van Kleeck. "Understanding the radiation belt environment and its variability has extremely important practical applications to spacecraft operations, spacecraft system design, mission planning and astronaut safety. The Aerojet team is confident our propulsion system will help deliver another mission success for NASA."

The two RBSP spacecraft will operate in nearly identical eccentric orbits. The orbits cover the entire radiation belt region and the two spacecraft will lap each other several times over the course of the mission. The RBSP in situ measurements will compare the effects of various proposed mechanisms for charged particle acceleration and loss.

While it was once thought that the behavior of the radiation belts was well-understood, observations over the last decade have generated new questions about the physical processes involved in the enhancement and decay of the belts and in the formation of new ones.

Aerojet is a world-recognized aerospace and defense leader providing propulsion and energetics to the space, missile defense, strategic, tactical missile and armaments areas in support of domestic and international markets. GenCorp is a leading technology-based manufacturer of aerospace and defense products and systems with a real estate segment that includes activities related to the entitlement, sale, and leasing of the company's excess real estate assets. Additional information about Aerojet and GenCorp can be obtained by visiting the companies' websites at and at